5 Methylene-2 hexanone

Methylene 2 hexanone, 47, 87 5 Methyl 5 hexen 2-one, 47, 87 Methyl hvdrazine, 46, 85 Methyl isocyanide, 46, 7S Methy lmagnesium bromide, reaction with bis(10,9 borazarophenan-thryl) ether, 46, 67 reaction w ith thiophosphoryl chloride, 45,102... 

Methylene ketones, such as cyciopentanone and cyciohexanone, are also readily acylated by boron trifluoride thus cyciohexanone (I) affords 2-acetylcycIo-hexanone (II) ... 

Thioxanthylium 1,2,3,4-Tetrahy-dro- -perchlorat E7a, 214 [2-(Arylthio-methylen)-cyclo-hexanon + (H3C —CO)20]... 

A Birch reduction of 2-methylanisole leading to methylenation has been described. The final step was effected by treatment of the intermediate, 3,6-dihydro-2-methyl-4-trimethylsilylmethylanisole with concentrated hydrochloric acid and aqueous tetrahydrofuran during 30 hours to give 4-methylene-2-methylcyck)hexanone in 60% yield (ref. 176). 

Gama-sitosterol Heptadecane Heptadecane, 9-octyl Heptane, 3-methylene Hexadecanoic acid 9-Hexadecanoic acid 2,4-Hexanedione 2-Hexanone Hexanal... 

In 2,5-dimethyl-3-hexanone, there are five different kinds of protons, labeled Hg-Hg in the figure. The six methyl protons, H, and the single proton, H, are neighbors. The methylene protons and proton are neighbors, but is also neighbors with the six methyl protons H. ... 

Interestingly, however, despite changes in cation and solvent, it is often stereochemical demands that dictate the product formed. For example, in the intramolecular cyclizations shown in Scheme 9.87,treatmentof5-bromo-3,3-dimethyl-2-pentanone with lithium diisopropylamide ([(CH3)2C]2N LT, LDA) in ether results in O-alkylation with the formation of 2-methylene-3,3-dimethyloxacyclopentane (2-methylene-3,3-dimethyltetrahydrofuran), despite the fact that carbon-oxygen bonds tend to be shorter (141 pm) than carbon-carbon bonds (154pm). On the other hand, the analogous 6-bromo-3,3-dimethyl-2-hexanone, under the same reaction conditions, produces 2,2-dimethylcyclohexanone. 

Scheme 9.87. The reaction of 5-bromo-3,3-dimethyl-2-pentanone with lithium dusopropyl-amide ([(CH3)2C]2N" Li, LDA) in ether resuiting in O-alkylation and the formation of 2-methylene-3,3-dimethyloxacyclopentane (2-methyiene-3,3-dimethyltetrahydrofuran) and the analogous reaction of 6-bromo-3,3-dimethyi-2-hexanone under the same reaction conditions to produce 2,2-dimethylcyciohexanone. (See Baidwin, J. E. Kruse, L. I. J. Chem. Soc., Chem. Commun., 1977, 233.)...

Methyl-l -benzoy lo methylen-cy ck hexanon-(6)-semica[Pg.2597]

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